Microprocessor-based computer processing systems frequently employ printed circuit boards (PCB's) containing connectors or sockets which physically hold the microprocessor chip and make electrical connection between the microprocessor and the remainder of the computer processing system via a PCB. Other common chip (microprocessor memory, etc.) mounting methods include either placing the pins of the chip through holes drilled in the PCB to which the chip will then be soldered or using what is known as surface mounting technology wherein a chip is merely placed on top of, and then soldered to, a printed circuit board. One of the advantages of surface mounting technology is the lower cost of manufacturing as well as avoidance of chip connector costs.
As computer processing system users require greater and greater processing capabilities, the ability to upgrade to a faster processor or add additional functions or features becomes more important. Presently the possible methods of upgrading a microprocessor-based computer processing system are to either replace the existing microprocessor with an improved microprocessor having additional functions or features and/or faster processing capabilities or, instead, to add separate upgrade componentry containing additional functions or features. For example, if a user requires faster mathematical processing capabilities the user has two options: 1) swap the microprocessor chip for a microprocessor chip which can run the same instruction set more quickly, or, 2) attach a math co-processor to the remaining original microprocessor chip which math co-processor would handle off-loaded mathematical calculations from the original microprocessor chip and thus improve overall processing speed.
One problem with adding a separate co-processor chip in order to provide additional functions, features, or performance to an existing processor chip is the performance degradation due to the signal delay between the original microprocessor chip and the upgraded function/feature/performance chip across the PCB which contains the two chips. For instance, in the math co-processor example above, because each mathematical calculation requires transmitting signals back and forth between the original microprocessor chip and the upgraded math co-processor chip, there is an inherent performance sacrifice due to the lower bandwidth of signal lines on a PCB as compared to a silicon wafer or chip.
Modern microprocessors increasingly combine multiple functions and features on a single integrated circuit chip. Such technology typically utilizes Large Scale Integration (LSI) and Very Large Scale Integration (VLSI) to achieve the necessary circuit density to be able to hold all the necessary componentry on a single integrated circuit chip. One of the benefits of increased circuit density, in addition to lowering power requirements, reducing heat generation and avoiding failure rates caused by faulty interconnects between separate chips, is in allowing greater processing speeds due to the ability to operate at the faster LSI or VLSI chip speeds rather than the slower printed circuit board speeds.
Thus, if a user desires to upgrade from a reduced performance chip to a LSI or VLSI all-in-one microprocessor chip in order to gain additional functions, features or performance, the user need merely remove the original microprocessor chip and replace it with the LSI/VLSI chip which can run the same instruction set as the original microprocessor chip. However, one problem with completely replacing the original microprocessor chip with an upgraded function/feature/performance LSI or VLSI microprocessor chip is the possibility of voiding whatever warranty may exist with regard to the entire computer processing system if this chip replacement is not done properly (either because the chip replacement was not done by an authorized technician or because replacement of the original chip might itself void the warranty).
Another problem with complete replacement of the original microprocessor chip with an upgraded function/feature/performance LSI or VLSI microprocessor chip is the requirement that the upgraded chip have identical pin-outs. Having identical pin-outs can be overly limiting in that it may be difficult to access additional functions or features without additional pin-outs to these functions or features.
Another limitation with complete replacement of the original microprocessor chip with an upgraded function/feature/performance LSI or VLSI microprocessor chip is the requirement that the upgraded chip have the same footprint and package type as the original microprocessor. Having the same footprint and package type would likely be necessary in order for the upgraded microprocessor chip to properly attach to the PCB in place of the original microprocessor chip.